1. Field of the Invention
The present invention relates to a tilt-type steering device in which the tilting-up angle of a steering shaft can be regulated.
2. Description of the Related Art
FIG. 9 illustrates a conventional tilt-type steering device. A steering shaft 02 disposed in a forward declined manner and having a steering wheel 01 at its rear end is supported at its front portion turnably in upward and downward directions by a pivot mechanism 03, and the position of the rear portion thereof is regulated up and down by a tilt mechanism 04. The front end of the steering shaft 02 is connected to a rear end of the joint shaft 05 through a rear universal joint 06, and a front end of the joint shaft 05 is connected to a steering gear box 07 through a front universal joint 08. The joint shaft 05 is declined forwards and has an intermediate portion passing through an opening 010 in a dashboard 09.
When a driver advancing under the action of inertia upon collision of the vehicle pushes the steering wheel 01 forwards, the steering shaft 02 is pushed forward along with the steering wheel 01. At this time, shock energy is absorbed by a friction force and a flexing deformation applied to an absorbing plate mounted in the tilt mechanism 04.
When the collision of the vehicle occurs, the dashboard 09 is moved rearwards by a shock. Further, when the steering gear box 07 is moved rearwards and downwards, the joint shaft 05 is pulled in an axial direction. When the joint shaft 05 is pulled in the axial direction, the position of the rear universal joint 06 is lowered, and the pivot mechanism 03 is also pulled down. This causes the steering shaft 02 to be tilted upwards while being moved forwards and downwards, and the position of the steering wheel 01 therefore rises.
When the steering shaft 02 has been tilted upwards in this manner, the load consisting of the push of the steering wheel 01 forwards by the driver upon the collision of the vehicle is difficult to transmit in an axial direction of the steering shaft 02. As a result, not only is there a reduction in the shock absorbing ability of the absorbing plate mounted in the tilt mechanism 04, but there is also a possibility that an air bag mounted in the steering wheel 01 does not properly expand toward the driver.
The present invention has been developed with the above circumstance in view, and it is an object of the present invention to prevent the steering shaft from being tilted due to the collision of the vehicle.